No, the AI can not adapt and use NEW units. AI play would have to be modified, which is beyond my skills.
However, the AI will use existing Enhanced Units that have been modified. Not tested on other unit sets.
Examples. I've modified the strength and range of all artillery and the AI uses it well. Increase the speed and/or carry capacity of any unit and the AI will use it.
Most of my games are with humans, or a combination human and AI.